In small bowl, soak black mushrooms in warm water to cover for 30 minutes; drain. Cut off and discard stems; thinly slice caps. Set aside. Meanwhile, in 3 quart saucepan over medium heat, in hot butter, cook onion 5 minutes or until soft. Add black mushrooms, fresh button mushrooms and oyster mushrooms. Cook 5 minutes or until mushrooms are soft and liquid has evaporated. Add half-and-half, chicken broth and oyster sauce. Heat to boiling. In covered blender or food processor, blend half of the soup at a time until smooth. Return to saucepan; heat through. Garnish with mushrooms and cilantro.